Points worthy of notice on forged steel valve operation-part one
Feb 14, 2019
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Regarding the forged valve, it is necessary not only to install and protect, but also to operate.
(1) The opening and closing of manually-operated valves.
A manually-operated valve is the most widely used valve. Its hand wheel or handle is designed according to the usual manpower. The strength of the sealing surface and the necessary sealing force are considered. Therefore, it is prohibited to use a long lever or a long wrench to push its hand wheel or handle. Some people are accustomed to using the wrench, which is definitely impermissible. In the opening and closing of the forged valve, do not push the handwheel too hard, that is, too excessive force is inadvisable, otherwise the sealing surface will be directly damaged, or the hand wheel will be broken off. We should use the appropriate force smoothly and steadily to open and close the forged valve. Some high-pressure forged valves are opened and closed by impact forces, whose components have now been reconsidered for such impact is not suitable for common forged valves.
In regard to the steam forged valve, before opening, it should be preheated and the condensed water should be removed. The steam forged valve should be opened slowly to the greatest extent, in order to prevent the appearance of water attack. When the forged valve is fully open, the handwheel should be pushed in reverse to a small extent to make sure the threads are tightly connected to prevent the loosening and damage.
With regard to the rising stem forged valve, it is necessary to remember the orientation of the stem when fully open and fully closed to prevent the top dead center from being hitting when the forged valve is fully opened. And it should be easy to see if it is normal when it is fully closed. On condition that the valve clack is dropped, or that large debris is embedded between the valve plug seals, the position of the stem will change when fully closed.
When the pipeline is used initially, there is much internal dirt. In this case, we could slightly open the forged valve and utilize the high-speed activity of the medium to wash away the impurity, and then close the forged valve slowly (it cannot be closed quickly or violently in order to prevent residual impurities from scratching the sealing surface). Operate the above steps again and again until all the impurity is cleared up. After the washing away, the pipeline can be put it into normal operation. For the forged valve that is going to be frequently opened, the sealing surface can be stuck with dirt, and when it is closed, it should be washed and cleaned by the above method, and then officially closed tightly. If the hand wheel or the handle is damaged or thrown away, it should be immediately equipped. It should not be replaced by a live wrench; otherwise, the surrounding of the valve stem would be damaged, which might contribute to the failure of the opening and closing, resulting in a trouble during production.